[cfe-dev] math.h on Windows

[Chris Lattner]

On Oct 28, 2009, at 11:08 AM, John Thompson wrote:

> Hi Chris and Doug,
>
> Here's a patch with my initial stab at "__has_include" and  
> "__has_include_next", along with a test for it (has_include.c) and  
> the modified stdint.h.

Awesome, thanks for working on this John, some thoughts:

* these should be documented in the clang language extensions document.


+++ include/clang/Basic/TokenKinds.def	(working copy)
@@ -83,6 +83,10 @@
  PPKEYWORD(assert)
  PPKEYWORD(unassert)

+// Clang Extensions.
+PPKEYWORD(__has_include)
+PPKEYWORD(__has_include_next)

Can this be implemented like __has_builtin is?  This is actually  
registered as a macro (in lib/Lex/PPMacroExpansion.cpp) which allows  
people to do things like:

#if defined(__has_builtin) && __has_builtin(__builtin_foo)

for example.


__has_include "stdio.h"

I think it is best to require ()'s, for similarity with __has_builtin  
and to allow people without this feature to #define it away.


@@ -244,9 +244,14 @@
      return CurPPLexer == L;
    }

-  /// getCurrentLexer - Return the current file lexer being lexed  
from.  Note
+  /// getCurrentLexer - Return the current lexer being lexed from.   
Note
    /// that this ignores any potentially active macro expansions and  
_Pragma
    /// expansions going on at the time.
+  PreprocessorLexer *getCurrentLexer() const { return CurPPLexer; }
+
+  /// getCurrentFileLexer - Return the current file lexer being lexed  
from.  Note
+  /// that this ignores any potentially active macro expansions and  
_Pragma
+  /// expansions going on at the time.
    PreprocessorLexer *getCurrentFileLexer() const;

Please apply separately.

  /// This code concatenates and consumes tokens up to the '>' token.   
It returns
  /// false if the > was found, otherwise it returns true if it finds  
and consumes
  /// the EOM marker.
-static bool ConcatenateIncludeName(llvm::SmallVector<char, 128>  
&FilenameBuffer,
-                                   Preprocessor &PP) {
+bool Preprocessor::ConcatenateIncludeName(

This set of changes is ok with me, please apply it separately to  
mainline.

+/// EvaluateDefined - Process a 'defined(sym)' expression.
+static bool EvaluateDefined(PPValue &Result, Token &PeekTok,
+        DefinedTracker &DT, bool ValueLive, Preprocessor &PP) {

Splitting this out makes sense to me, but please do it as a separate  
commit.

>
> Since these are Clang-specific keywords (I think), perhaps they  
> should be disabled in some circumstances (i.e. language mode), but  
> I'm not sure how, and I haven't look much into it yet how it is done  
> elsewhere in the code.

This can be done by just not registering the 'magic' macros in no- 
extensions mode.  Please apply the pieces above as independent  
patches, and try restructuring your approach around magic macros to  
follow the lead of __has_feature and __has_builtin, sending in that  
patch for review.

Thanks again John,

-Chris